Apparatus for phosphorus recovery



Nov. 24, 19436. s. D. GoocH APPARATUS FOR PHOSPHORUS RECOVERY FiledMarch 25, 1935 2 Sheets-Sheet 1 NSE@ Nofv. 24, 1936. l s, D @300m-l2,062,091

APPARATUSy FOR PHOSPHORUS RECOVERY Patented Nov. 24, 1936 UNITED STATESlnxrlszlu'lj,v OFFICE 2,062,091 l- APPARATUS Fon PnosPHoRUs RECOVERStapleton D. Gooch, Pembroke, Fla.

Application March 23, 1935, Serial No. 12,693

' s claims. (c1. zei- 111) My invention relates to apparatus for thesep- .aration of phosphorus from furnace gases, and more particularly tothe separation of phosphorus from blast furnace gases in whichphosphorus vapors are relative dilute.

In the treatment of gases from blast furnaces containing phosphorusvapor to recover phosphorus, the large quantity of gases to be treatedcreates dicult problems. In condensing equipment which employs a coolingliquid having direct contact with the gases, because the gases are insuch large volume, difficulties of construction are encountered. Tohandle large volumes of gas moving at relatively high velocity wouldordinarily necessitate the employment of large condensing equipmentunits, whichy would be costly in installation and maintenance, and butpartially efcient.

The smaller the size of the condensing equipment, the faster the flow ofthe condensing and cooling medium employed, and likewise the faster -theiiow of the gases to be treated. AWhen these factors are consideredtogether with the prime necessity of preventing access of oxygen to thecooling liquid, the diiliculties of constructing eiilcient smallcondensing equipment can be readily appreciated. A

It is an object of my invention to provide a spray chamber, receivingtank, overflow tank and spray catcher equipment which may be constructedat small cost, and is of high efficiency in handling large volumes ofgas in` a short period of time.

. It is a further object of my invention to provide equipment for thecondensation of phosphorus which is safe in operation, and which willmaintain a high degree of eillciency in obtaining phosphorus from adilute vaporous form in furnace or ue gases. y

With these and other objects in view, my invention consists in the partsand combinations to be hereinafter set forth and claimed, with theunderstanding that the several ,necessary elements may be .varied inproportions and arrangements without exceeding the scope of the appendedclaims. f

, In order to more fully explain my invention, 1 have shown in theaccompanyingdrawings certain constructions which may be subject tomodication without avoiding the spirit of the invention, but which areillustrative and explanatory of one mode of applying my invention.

In the drawings:

Figure 1 is a diagrammatic illustration 0I my phosphorus condensingsystem;

Fig. 2 is a cross'sectional view taken through the axis of the rstcondenser, showing the spray catcher partly in section, and thereceiving tank and the overflow tank in section;

Fig. 3 is a view taken along the line 3-3 of 5 Figure 2, looking in thedirection of the arrows;

Fig. 4 is a view taken along the line 4 4 of Figure 2, looking in thedirection of the arrows;

Fig. 5 is a detail view taken along the line 5 5 of Figure 4, looking inthe direction of the arrows; 1C

Fig. 6 is a view in side elevation diagrammath cally showing thearrangement of the third condenser and the spray catcher therefor; Fig.7 is a view in side elevation diagrammatically showing the coolingsystem. 15

In the drawings, most of the showings have been made diagrammatically inorder to avoid unnecessary v details of ,the showings made of standardparts of vapparatus which are familiar to those skilled in the art. 20

The ue gases of the phosphorus furnace which are rich in phosphorus,which is in vapor form, enter a conduit I and passte a dust catcher 2where a large portion of the dust settles. From the top of the dustcatcher is a conduit 3 which 25 leads to 'a dirty gas main 4 which is aheader. From the dirty gas main I are conduits 5 which lead to threevortex cleaners 6. These cleaners are of the cyclone type and arearranged in parallel. Here the gas, which still contains a consid- 30erable amount of dust, is cleaned by centrifugal action. From the threeVortex or cyclone type cleaners the gas, which is now relatively dustfree, passes to conduits 'I and into a clean gas main 8, which serves asa header for the conduits 1. 35

From the clean gas main 8 the phosphorus-containing vapors pass to aconduits which connects witha conduit I 0.

The temperature of the flue gases which entered the conduit II has nowbeen quickly reduced to a 40 point above the dew point of the phosphorusvapor, but below that temperature at which there will be any markedtendency for the phosphorus to assume the allotropic red form.

From the conduit I0 the iiue gases containing 45 the phosphorus vaporspass into the lower end of At the upper part of the spray chamber I I isan outlet passage I4 through which are adapted to pass the gases withentrained moisture in droplet form, as well as the phosphorus vaporwhich 5 has not been condensed in this irst condenser. 'I'he conduit I0is located on the opposite side of the spray chamber II from the outletconduit I4, andthe entrance points of the two conduits into the spraychamber are separated practically by the length-of this chamber.

volume of gas to be subjected to a thorough spraying in its travelthroughout the length of the chamber.

From the outlet passage I4 the mixed gases and vapors together with theentrained droplets of cooling liquid, which may be a slightly acidulatedaqueous solution, pass into a spray catching tank I5 which is providedwith an outlet I6. It is to be noted that the conduit I4 delivers thestream of gases and vapors together with the entrained droplets ofcooling liquid substantially tangentially against the interior walls ofthespray catching tank I5, and that the conduit I4 and the conduit I6are located, respectively, near the bottom and the top of the spraycatching tank I5. The whirling motion of the material delivered by theconduit I4, causes it to impinge against the side walls of the tank I5,tending to deposit the droplets of cooling liquid against the walls.

Because of the staggered relationship of the conduits I4 and I6, thematerial delivered into the tank I5 mustpa'ss through a tortuous pathbefore it arrives at the conduit I6, thus tending to precipitate thedroplets. In this spray catching chamber I5 is deposited' a largeportion of the entrained droplets which fall into a conical bottom IIand pass into a conduit IB from which the cooling liquid is deliveredinto a receiving tank I9 l l at a point below the surface of the coolingliquid in the receiving tank. The outlet of the conduit I9 issuficiently below the surface of the cooling liquid in the receivingtank I9 so that the pressure of the gases and vapors in the apparatusshall, not be sulcient to permit a bubbling of such gases and vaporsfrom the lower end of the conduit- I6.

'I'he spray chamber II is provided with a conical bottom 20 having anoutlet 2I located at the apex of the inverted cone which forms thisbot,- tom. Chamber I I is so located with respect to the liquid level inthe receiving tank I9 that the pressure of gases and vapors in thesystem shall not be sufficient to cause the liquid in the lower end ofthe spray chamber I I to fall below the base of the inverted cone 20which forms the bottom of the spray chamber II.

One of the problems in obtaining proper collection of the phosphorus isvto provide for the treatment of a large volume of gases and vaporsmoving at relatively high velocity in order to conserve the size of theunits used, and at'the same time to provide quiet settling zones whichwill permit the phosphorus to collect and to cool without/ beingsubjected to turbulent currents of cooling liquid. Because the base ofthe inverted cone which forms the bottom of the spray chamber is locatedwell below the surface of the liquid in the receiving tank, the drops offalling cooling liquid always strike a surface of liquid at the lowerend of the spray chamber which is of a maximum area. Yet

the sloping walls of the conical bottom tend to concentrate thephosphorus-containing liquid into a relatively small outlet which, aswill be later apparent, directs the phosphorus containing liquid towardsthe locus in which the settling is consum- 115 mated.

This .permits the I'he receiving tank I9 is formed with cylindrical sidewalls 22 and a conical bottom 23 which is in the yform oi' an invertedcone having an apex -24 in which is adapted to collect the liquid phos'phorus. The temperature of the cooling water 5 and the speed of flow o1'the phosphorus-containing gases and the other factors are so regulatedthat the phosphorus shall remain in liquid form at the apex 24 of theconical bottom 23, from which it may be withdrawn by a pump (not shown)10 to storage, or further treatment. The phosphorous in liquid form iswithdrawn through the pipe 24.

AThe interior of the receiving tank I9 is lined with an acid-resistingbrick 2,5. 'I'he` acidresisting brick 25 is built up into a circularwall at 26 and so constructed as to form a trough 21. This constructionprovides an overflow trough into which the cooling liquid overflows fromthe receiving tank I 9, The cooling liquid containing the moltenphosphorus passes down through the outlet 2I and is directed towards theapex 24 of the conical bottom 23 of the receiving tank I9.

A relatively large volume of lcooling liquid is circulated through thereceivingY tank and the spray chamber, but it will be noted that becauseof the path-in which this liquid is directed and by reason of the factthat there is a large cross sectional area of liquid 'adjacent the lowerpend of the outlet 2l of the spray chamber, the liquid is not turbulentat this point and there can be, and is, an efllcient settling of theliquid phosphorus into the apex 24- of the conical bottom 2 3. Thisconstruction permits a large volume of cooling liquid to be employed andyet provides a quiescent zone in which the liquid phosphorus mayaccumulate. The liquid phosphorus is but relatively slightly disturbedin its travel to 24, because of the comparative lack of turbulence ofthe cooling liquid either in the bottom of the spray chamber, 40 or inthe zone adjacent and below the outlet from the spray chamber.

'I'he overflow trough of the receiving tank communicates with a conduit28, which likewise connects with a downwardly directed inletpipe 29, 45

,which latter passes through a cover 36 of an overilow tank 3| that isadapted to catch the over- 'ow of the cooling liquid from the receivingtank I9. The receiving tank I9 is likewise provided 'with a cover 32, asshown in the drawings.

In the cover 30 is provided a manhole 33 `(see Fig. 5). Mounted aroundthe edge of the manhole 331s a trough 3 4 adapted to be partially lledwith a sealing liquid 35. 'I'here is a manhole cover 36 that has adownwardly extending lip 31 that lits within the trough 34, and isadapted t0 have its lower edge pass below the surface of the sealingliquid 35. `This construction provides an airtight ilti'or the overowtank, yet should there be violent iluctuations in the pressure of thegases and vapors, as sometimes occurs under the best possible operatingconditions, the manhole cover will permit escape of the high pressuregases generated with a minimum of damage to the apparatus. At the sametime, and most importantly, the access of oxygen to/'the cooling liquidis prevented.

Within-an aperture in the cover 30 of the overflow tank, there isprovided a downwardly extending telltale casing 33 whose lower, open endis near a bottom wall 39 of the overflow tank. In this telltale casing Ihave a telltale which comprises a iloat 40 and an indicating rod 4I.I'his arrangement permits 'the operator to ascertainfr the height of thecooling liquid in the overilow tank, yet it allows only a minimum ofaccess of oxygen to the cooling liquid, since the only oxygen-exposedsurface of the cooling liquid is that which lies within the telltalecasing' 3 8, and this liquid is, moreover, subject to but slowdisplacement from the cooling liquid in the overflow tank.

Conduit 42 carries the cooling liquid from the overflow tank to anoverflow ditch43. In the spray catching tank I5 I h-ave providedflushing nozzles 44l which may be used to flush out the spray catchingtankt|5 and the conduit4 8,.when desired, with hot liquid to preventaccumulations on the interior surface. I have not shownconnections tothe nozzles-44, in order to simplify the showing.

The conduit I6 from the spray catching tank I5 leads to the bottomof asecond spray chamber 45 similar in construction to the spray chamber II. The spray chamber I I and accompanying apparatus I have designated inthe drawings, Figure l, as No, 1 condenser. Phosphorus in liquid form iscollected at the bottom of `a receiving tank 46 and is pumped out'tostorage, or' further treat' ment. This combined :receiving tank 'andspray chamber is designated onthe drawings as No. 2 condenser. A

An outlet conduit 41 from the spray chamber 45 leads to the bottom of aspray chamber.

rially reduced by reason of the cooling to which later described. 'I 'hecombined spray chamber 48 and receiving, tank 5| Id'esignate on thedrawings as No. 3 condenser.

From the top of the spray chamber 48 the gases and vapors pass throughs.conduit 5 8 to the bottom of a spray catcher 51. The conduit 56 isadapted to deliver \t he gases and vapors substantially tangentiallyagainst the interior walls of the spray catcher 51. The spray catcher 51is provided at its top with an outlet conduit -58 through which thegases pass out, and may be then employed i'or` combustion purposes. Thedotted arrows indicate that the gases follow a tortuous path in thespray catcher and the entrained cooling liquid droplets are caught inthis part of'the apparatus. The liquid can be withdrawn from the bottomthrough pipe 51' and returned to the receiving" tank 5|.

It is a very important feature of thisv system that the gases bele-oxidized initially and kept de-oxidized throughout the operation.otherwise ,phosphorus oxide sludges are formed in the apparatus whichnot only reduce the yie1d,'but closr the apparatus. The cooling systemin which I employ a cooling liquid is described in the copendingapplication of Kerschbaum and Goof'h,`

Serial No. 680,504. 'This application shows the method which I employ toobtain this initial deoxidation of the cooling iluid and its continuousde-oxidatlon during use.

In the cooling system shown in the drawings,

tank |0I. an voverflow tank of similar construction |02.

Figures 1 and 7, I employ a vacuum evaporator for cooling andde-oxidlzing. This is of a Well known type using steam jets to obtain avacuum, (not shown for purposes of simplicityf in description). 'I fhevacuum draws out of thev cooling liquid dissolved gases, reducing theoxygen content to a desirableminimum. The cooling liquid is cie-oxidizedprior to its introduction into the condensers 1, 2 and 3, and by theoperation of the vacuum evaporator I maintain the cooling liquid cooland relatively oxygen free during operation of my system. It is to beunderstood thatthe vparticular cooler is no part of this invention solong as it performs the function of deoxidizing and cooling. Inl thedrawings I have designated the cooler by the numeral |00, and it isentitled on the drawings Vacuum evaporator for cooling and de-oxidizing.

I have., shown in the drawings two overiiow tanks for the No. 1condenser, the overflow tank 3| 4previously described, and a similaroverflow For the No. 2 condenser I have shown Both overflow tanks IDIand |02 may discharge into the overflow ditch 43. 'The overflow tank |02may discharge also into av conduit |03 provided with a valve |04 fromwhence the liquid passes toja storage tank |05. From the storage tank|05 the cooling liquid is drawn through an outlet conduit |06 .anddischarged at |01 into the vacuum evaporator |00.

Vapors from the vacuum evaporator pass to a condenser |08 where they arecondensed and are discharged-through a conduit |09 to a suitabledrainage ditch ||0. In the vacuum evaporator |00 the cooling liquid,which-maycomprise an aqueous medium of acidity from say approxi- -mately11u-normal to 1normal, is de-oxidized and cooled and ilows out through adischarge conduit III which feeds conduits II2 and I|3 through valves||4 and. II5, respectively. The conduits I2 and I|3 lead to centrifugalpumps IIB and ||1, respectively, through which cooling liquidis sprayedinto the top ofthe spray chamber 45 oi' theNo. 2 condenser.

When the plant is once o'n stream, the cooling liquid is recirculatedalong the path previously indicated. at the time of starting the plant,the storage tank |05 is fed through a conduit I8 cont'rolled by .a valveII9 which initially charges the Astorage tank -with cooling liquid sothat it can be de-oxidized prior to the introduction of the coolingliquid into the cooling system comprisingthe condensers No. 1. No. 2 andNo. 3.

There-is provided a branch pipe |20 which connects with the output pipefrom pump ||1 which supplies cooling liquid to the sprays for thespray'l condenser equipment. Control valves |21 and |28 are locatedrespectively in the lines |25and |28.

Through lthe line |26 cooling liquid suflicient for No. 1- condenser Vtostart operation can be suppliedn Intermittently 'and from time to timeas thecoolingr liquid in the No. 1 condenser system needs replenishment,this can be effected through line |25. The cooling liquid for the No. 1'con- 'have provided means for treating large volumes of gas containingphosphorus vapors flowing at high velocities with large quantities ofcoolingv liquid, 4while getting high yields of phosphorus with verysmall formation of objectionable oxides.

While I have shown and described thepreferred embodiment of myinvention, I wish it to be understood that I do not'conflne myself totheprecise details of construction herein set forth by way of illustration,as it is apparent that many changes and variations may be made therein,by those skilled, in the art. without departing, from the spirit of theinvention, or exceeding the scope of the appended claims.

I claim:

l. In an apparatus for the condensation of phosphorus from the vaporform, a spray chamber having a conical bottom provided with a liquidoutlet passage at the apex of the conical bottom, spray means in the topof the spray chamber to spray cooling liquid therein, said spray chamberbeing provided with an inlet passage for the phosphorus vapors near thebottom thereof, and an outlet passage for the uncondensed vapors andgases near the top thereof, a receiving tank below the spray chamberhaving side walls and a conical bottom to receive the condensedphosphorus and the cooling liquid from the spray chamber and vallow thecooling liquid to collect therein in a quiescent pool, means to withdrawthe phosphorus from the conical bottom of the receiving tank, an'overflow trough inside of the receiving tank located on the side wallsthereof, the upper edge of the overflow trough being sufficiently abovethe end of the liquid outlet passage from the spray chamber that aquiescent pool is formed in the spray chamber of substantiallythediameter of the chamber, and means to withdraw the cooling liquid fromthe overflow trough.

2. In Ian apparatus for the condensation of phosphorus from the vaporform, a spray charnber having a bo-ttom in the form' of an inverted coneprovided with a liquid outlet passage at the apex of the conical bottom,spray means in the top of the spray chamber to spray cooling liquidtherein, said spray chamber being provided with an inlet passage for thephosphorus vapors near the bottom thereof and an outlet passage foruncondensed vapors and gases near the top thereof on the opposite sidefrom the inlet passage; a receiving tank below the spray chamber havingside walls and a bottom in the form of an inverted cone to receive thecondensed phosphorus and the cooling liquid from the spray chamber andallow the cooling liquid to collect therein inga quiescent pool, means vto withdraw the phosphorus from the conical bottom of the receivingtank, an overflow trough inside of the receiving tank located on theside walls thereof, the upper edge of the overflow trough. beingsufficiently above the base of the inverted cone which forms the bottomof the spray chamber that a quiescent with an inlet passage for thephosphorus vapors near the bottom thereof and an outlet passage foruncondensed vapors and gases near the top thereof on the opposite sidefrom the inlet passage, a receiving tank below the spray chamber havingside walls and a bottom in the form of an inverted cone to receive thecondensed phosphorus and the cooling liquid from the spray-chamber andallow the cooling liquid to -collect therein in a quiescent pool, meansto withdraw the phosphorus from the conical bottom of the receivingtank, an overflow trough inside of the receiving tank located on theside walls thereof, the upper edge of the overilow trough being at sucha height above the base of the inverted conewhich forms the bottom ofthe spray chamber that the spray always falls on an area of water ofmaximum diameter and a quiescent pool of water is formed in the spraychamber, and means to withdraw thev lcoolingliquidfm the overow troughand recir-l culate it to the spray means.

4. In an apparatus for the .condensatlonof phosphorus from the vaporform, a spray chamber, spray means therein to spray a cooling liquid onthe phosphorus contained vapor, an outlet conduit from the spray chamberinto which is adapted to pass phosphorus containing vapors havingentrained moisture in drop form, acylindrical spray catching ytank towhich the outlet conduit feeds at a low point, said conduit deliveringsaid stream substantially tangentially against the interior walls of thetank, a vapor conduit of moisture are adapted to pass, said last men-'tioned conduit being located above the first menposited therein to alocus from which it may be recirculated in the spray chamber. I

5. In an apparatus for the condensation of phosphorus from the vaporform, a spray chamber having a lconical bottom provided with a liquidoutlet at the apex of the conical bottom, spray means in the top of thespray chamber to spray cooling liquid therein, said spray chamber beingprovided with an inlet passage for the phosphorus vapors near the bottomthereof, an outlet passage foruncmdensed vapors and gases near the topthereof, a cylindrical spray catching tank to which the outlet conduitfeeds at a low point in that tank, said conduit delivering a stream ofphosphorus vapors and gases with through which the vapors after theirdeposition I the spray catching tank forxreturning liquid dephorus andthe cooling liquid from the spray 75 chamber and allow the coolingliquid to collect therein in a quiescent pool, means to withdraw thephosphorus from the conical bottom of the receiving tank, an overflowtrough inside the re,- ceiving tank located on the side walls thereof,the upper edge of the overflow trough being above the outlet passagefrom the spray chamber, means to withdraw the cooling liquid from theoverflow trough, and a return conduit leading from the low point in thespray catching tank for returning liquid deposited therein to thereceiving tank.

6. In an apparatus for the condensation of phosphorus `from the vaporform, a spray chamber having a conical bottom provided with a liquidoutlet at the apex of the conical bottom,-

spray means in the top of the spray chamber to spray cooling liquidtherein, said spray chamber being provided with an inlet passage for thephosphorus vapors near the bottom thereof, an outlet passage foruncondensed vapors and gases near the top thereof and on the oppositeside from the inlet passage, a cylindrical spray catching tank to whichthe outlet conduit feeds at a low point in that tank, said conduitdelivering a stream of phosphorus vapors and gases with entrainedmoisture droplets therein substantially tangentially against theinterior -walls of the spray catching tank, a vapor conduit throughwhich the vapors after their deposition of moisture are adapted to passfrom the spray catching tank, said last mentioned conduit being locatedabove the outlet conduit from the spray chamber and in staggeredrelation thereto. a receiving tank below the spray chamber having sidewalls and a bottom in the form of an inverted cone to receive thecondensed phosphorus and the cooling .liquid from the spray chamber andallow the flow trough being at such a height above the base oftheinverted cone which forms the bottom of the spray chamber that the sprayalways falls on an area of water of maximum diameter, means to withdrawthe cooling liquid from the overiiow trough, and a return conduitleading from the low point in the spray catching tank for returningliquid deposited therein to the receiving tank, said return conduithaving its end in the return tank atsuch a distance below the liquidlevel therein that bubbling due to pressure of gases and vapors in thespray catching tank is avoided, andl means to withdraw the coolingliquid from the overflow trough and recirculate it to the spray means.

7. In an apparatus for the condensation of phosphorus from the liquidform, a spray chamber having a conical bottom provided with a liquidoutlet passage at the apex of the conical bottom, spray means in the topof the spray chamber to spray cooling liquid therein, a receiving tankbelow the spray chamber having side wa1ls,/ an overflow trough inside ofthe receiving tank located on the side walls thereof, the upper edge ofthe overflow trough being sufficientlyv above the end of the liquidoutlet passage from the spray chamber that a quiescent pool is formed inthe spray chamber of substantially the diameter of the chamber.

8. In a phosphorus condensing apparatus, a spray chamber, aspraycatching tank, an outlet conduit from thespray chamber into the spraycatching tank which is adapted to pass phosphorus containing vaporshaving moisture in drop form into the spray catching tank,l said conduitleading into the spray catching tank at a low point and delivering saidstream of phosphorus containing vapors substantially tangentiallyagainst the interior walls of the spray catching tank, and a secondconduit at a high point in the spray catching tank serving as an outletfor the gases and Vvapors from that tank.

STAPLETON D. GOOCH.

